(1):
(n.) A person sent secretly into an enemy's camp, territory, or fortifications, to inspect his works, ascertain his strength, movements, or designs, and to communicate such intelligence to the proper officer.
(2):
(n.) One who keeps a constant watch of the conduct of others.
(3):
(v. i.) To search narrowly; to scrutinize.
(4):
(v. t.) To explore; to view; inspect; and examine secretly, as a country; - usually with out.
(5):
(v. t.) To discover by close search or examination.
(6):
(v. t.) To gain sight of; to discover at a distance, or in a state of concealment; to espy; to see.